1929 Willys-Knight Tire Fitment Guide

1929 Willys-Knight vehicles use four sizes across two models. The 66B Series uses 31X6.00 and 600-19, while the 70B Series uses 29X5.50 and 550-19. All of those sizes are bias-ply fitments, and the available product listings shown here place the supported numeric sizes on 19-inch rims, with 550-19 specifically calling for a 2.50 to 3.00 inch rim width.

The practical takeaway is that a 1929 Willys-Knight owner needs to identify the model first, not just the year and make. Once the car is confirmed as a 66B Series or 70B Series, the next step is choosing the correct size family for that model and then matching the wheel dimensions to the tire before moving on to sidewall style or brand preference.

On a 1929 Willys-Knight, 31X6.00 is an antique diameter-by-section size. The first number, 31, refers to the tire's overall diameter in inches, and the second number, 6.00, refers to nominal section width. That differs from later numeric sizing because the code emphasizes the tire's outside diameter rather than ending with the wheel diameter in the size itself.

That matters because a modern buyer may confuse 31X6.00 with a contemporary flotation size, even though it belongs to an earlier sizing convention. On a 1929 Willys-Knight, this size is tied specifically to the 66B Series, so it should be treated as a model-correct period fitment rather than as an interchangeable size for every Willys-Knight sold that year.

On a 1929 Willys-Knight, 600-19 and 550-19 are numeric bias-ply sizes. The first part, 6.00 or 5.50, gives the nominal section width in inches, and the last number, 19, is the wheel diameter in inches. That format is more familiar to many collectors because it directly states the rim size and became common on many late-1920s and 1930s applications.

Those two numeric sizes are not interchangeable across the full 1929 Willys-Knight range. The 66B Series uses 600-19, while the 70B Series uses 550-19, and available 550-19 products also show a 2.50 to 3.00 inch rim width range. Numeric sizing is often the simplest place to start when comparing products, but it still needs to match the correct model.

1929 Willys-Knight tire choices include both blackwall and whitewall styles, depending on size. The available 600-19 option is a Lester Wide Whitewall, while 550-19 is offered by BFGoodrich in both Blackwall and Wide Whitewall forms. Those sidewall differences change the visual character of the car even when the construction and general period look remain rooted in bias-ply design.

For a restoration-minded owner, sidewall style should be chosen with the car's intended presentation in mind. A blackwall often suits a more understated period appearance, while a whitewall brings a more dressed, upscale look that many late-1920s American cars wore well. If authenticity matters for a specific event or market version of a 1929 Willys-Knight, compare your car against period photos and marque-club guidance before finalizing the look.

Current product coverage for 1929 Willys-Knight vehicles includes Lester and BFGoodrich. Lester appears in 600-19 with a Wide Whitewall option for the 66B Series, while BFGoodrich appears in 550-19 for the 70B Series with both Blackwall and Wide Whitewall versions. All of those listed choices are bias-ply products that suit the era of the car.

Brand choice on a 1929 Willys-Knight usually comes after the model and size are settled, because the product range differs by fitment. A 66B Series owner shopping 600-19 is choosing within a different brand set than a 70B Series owner shopping 550-19. That makes it smart to narrow the search by model first, then compare appearance details such as sidewall treatment within the correct size.

For a 1929 Willys-Knight using 550-19, the two BFGoodrich Silvertown Classic Bias Ply choices share the same size, the same 19-inch rim diameter, the same 2.50 to 3.00 inch rim width range, and the same listed maximum load of 1040 pounds at 32 psi. The main difference is sidewall appearance, with one Blackwall version and one 3.25 inch Wide Whitewall version. The listed weights also differ slightly, at 21 pounds for the blackwall and 23 pounds for the whitewall.

That means the decision is mostly visual rather than structural for a 70B Series owner choosing between those two BFGoodrich products. If the car is being finished with a more formal late-1920s look, the whitewall changes the stance and presentation noticeably. If a plainer period look is preferred, the blackwall keeps the appearance more restrained while staying in the same size family.

Rim width guidance is available here for 1929 Willys-Knight 550-19 fitments. That size, used on the 70B Series, calls for a 2.50 to 3.00 inch rim width and mounts on a 19-inch wheel. The other listed sizes for 1929 Willys-Knight also mount on 19-inch rims, but the same explicit width range is not shown here for every size.

Wheel width matters because an otherwise correct vintage tire can behave poorly or sit incorrectly if mounted on a rim outside its intended range. On a 1929 Willys-Knight, confirm both the wheel diameter and the actual rim width before selecting a tire, especially if the car has replacement wheels or a long restoration history where parts may have been changed.

Tube fitment is not called out as a mixed product condition across the currently listed 1929 Willys-Knight offerings, and the available tires are all period-style bias-ply designs used on late-1920s applications. On cars of this era, tube use is commonly part of the overall wheel-and-tire system, especially with original-style rims and vintage construction practices. The exact setup should still be matched to the wheel design and the specific tire's sidewall marking.

Rather than assuming every 1929 Willys-Knight wheel should be treated the same, inspect the rim carefully before assembly. Original wheels, restored wheels, and replacement rims may differ in finish, sealing condition, and hardware details that affect tube choice. If the tire or wheel specialist recommends a tube, flap, or specific valve arrangement, follow that guidance for the exact components being used.

A 1929 Willys-Knight uses 19-inch wheel diameters across the listed size range, so the original wheel diameter is consistent between the 66B Series and 70B Series fitments. That does not make every size interchangeable, however, because the tire families remain model-specific: 31X6.00 and 600-19 for the 66B Series, 29X5.50 and 550-19 for the 70B Series.

The useful implication is that original 19-inch wheels may share diameter compatibility, but the final answer still depends on width and on the model's correct size family. Before mounting a different-looking size on a 1929 Willys-Knight, verify the wheel width and compare the car's current wheel set against the model it actually is. That avoids forcing a tire onto a rim or using a size meant for the other series.

A 1929 Willys-Knight should be stored in a cool, dry, dark space away from direct sunlight, electric motors, battery chargers, welders, and other ozone-producing equipment that can accelerate sidewall aging. Because these are bias-ply tires on a low-use collector car, long static periods can also encourage flat-spotting. Clean floors, stable temperature, and proper inflation help reduce stress while the car sits.

If the car is parked for extended periods, move it occasionally or support it in a way that reduces continuous loading on one contact patch. Many owners also keep the tires covered from light and inspect them after seasonal storage before resuming use. Good storage habits matter as much as tread depth on a 1929 Willys-Knight, because age and environment often determine service life sooner than mileage does.

Tires on a 1929 Willys-Knight usually age out before they wear out. A good collector-car rule is to begin evaluating them closely once they are around five to seven years old and to give serious replacement consideration as they approach ten years, even if the tread still looks usable. The manufacturing date can be checked through the tire's date code, and visible cracking, hardening, or repeated pressure loss can shorten that timeline.

Mileage alone is a poor guide for a lightly driven 1929 Willys-Knight because long periods of sitting can age the casing and sidewalls without adding many road miles. Keeping records of installation date, storage conditions, and inspection findings makes replacement decisions much easier. On vintage cars, conservative age-based replacement is usually wiser than trying to extract every possible mile from an old set of tires.

Tires on a 1929 Willys-Knight should be inspected before every drive and again before any extended outing. Look for sidewall cracking, tread separation, cuts, bulges, irregular wear, and any sign that pressure is dropping between uses. Since vintage wheel-and-tire systems can be sensitive to age and storage, valve stems and the spare deserve the same attention as the four road tires.

A brief walkaround catches many problems before they become roadside failures. On a collector car that may go weeks between outings, check pressure with a reliable gauge instead of relying on appearance alone, because a bias-ply tire can still look reasonably full while being underinflated. Building inspection into every pre-drive routine is one of the simplest ways to protect both the car and its passengers.

A 1929 Willys-Knight 66B Series would have been equipped in the bias-ply era, and the fitment family associated with that model here is 31X6.00 and 600-19. That combination reflects the transition period when antique diameter-by-section and numeric sizing conventions could both appear in collector fitment research for late-1920s American cars. Original-equipment brand should not be assumed without period literature or marque-specific confirmation.

For restoration work, the important first step is matching the 66B Series to its correct size family and then choosing the sidewall look that suits the car's intended presentation. If the car is being judged, period photos, factory literature, and Willys-Knight club resources can help confirm whether a particular numeric or antique-marked presentation is most appropriate. Getting the construction, size family, and visual style aligned is usually more important than chasing a brand assumption.

Correct tire fitment matters on a 1929 Willys-Knight because show judges and knowledgeable enthusiasts often notice whether the size family, construction type, and sidewall style fit the car's era and model. A 66B Series wearing 70B Series sizing, or a sidewall treatment that clashes with the car's intended presentation, can stand out quickly. On late-1920s cars, authenticity is often judged by the total impression as much as by any single measurement.

That does not mean every event applies the same standard. Touring events may be more forgiving than concours-style judging, while marque-specific meets can be stricter about details. If showing is part of the plan, use the correct model-specific tire size first, then compare your chosen sidewall style against period imagery and club guidance so the car looks consistent with how a 1929 Willys-Knight would have appeared in its own time.

On a 1929 Willys-Knight, antique sizes such as 31X6.00 and 29X5.50 express overall diameter first and section width second, while numeric sizes such as 600-19 and 550-19 express nominal width and wheel diameter. Both belong to the same broad bias-ply era, but they present the tire's dimensions through different period naming conventions. That distinction is especially relevant on late-1920s cars, where collectors often encounter both systems during restoration research.

For authenticity, the question is less about modern performance and more about which size convention best matches the model and the look you want the car to project. A 66B Series should stay within its own 31X6.00 or 600-19 family, and a 70B Series should stay within its 29X5.50 or 550-19 family. If you are building for judged presentation, compare sidewall markings and period references rather than assuming any same-diameter tire will read as correct.

1929 Willys-Knight tires can be suitable for road use when they are the correct size, in sound condition, and used within the expectations of a late-1920s bias-ply vehicle. The currently listed 550-19 products do not show multiple modern speed-rating variations, so the larger question is usually the overall condition of the tire and the car rather than choosing among speed-rated versions. On a vehicle of this age, brakes, steering, suspension, wheel condition, and driver expectations matter at least as much as the tire itself.

Highway use should be approached with the habits appropriate to a 1929 Willys-Knight rather than a modern sedan. Keep speeds sensible, avoid long runs on aged tires, and pay close attention to inflation, temperature, and vibration during the drive. A freshly inspected bias-ply tire on a well-sorted vintage car can be enjoyable on the road, but the full mechanical package must be ready for that kind of use.

Inflation pressure on a 1929 Willys-Knight should be matched to the exact tire size, the tire maker's stated rating, and the vehicle guidance for the specific model. The listed 550-19 BFGoodrich products show a maximum load of 1040 pounds at 32 psi, which is a tire rating reference rather than a blanket setting for every 1929 Willys-Knight tire. Pressure should never be transferred from one size family to another without confirming the tire and vehicle requirements.

The safest approach is to start with the car's factory recommendations if you have them, then compare that information with the reproduction tire's own sidewall and manufacturer guidance. A 66B Series on 600-19 should not automatically be set by figures shown for 550-19, and the same caution applies to antique-marked sizes. Correct pressure affects wear, steering feel, ride quality, and casing stress, so it is worth verifying before regular use.

Before a longer drive in a 1929 Willys-Knight, inspect each tire for cracking, cuts, bulges, exposed cord, irregular wear, and proper inflation. Check the valve stems, confirm the spare is usable, and make sure the wheels and lug hardware are in good condition. Since these cars rely on period-style bias-ply tires, a careful tire inspection should be part of a broader review that also includes brakes, fluids, cooling system, steering, and lighting.

A short local test drive before a major outing can reveal pull, shimmy, vibration, or heat buildup that is easier to address close to home. It is also wise to revisit the model-specific tire choice itself, especially on a recently acquired car, to make sure a 66B Series is not wearing 70B Series sizing or the reverse. Longer trips are far more enjoyable when the tire condition and the rest of the chassis have both been checked with equal care.